How To Avoid Nearsightedness
The formulation of a problem is often far more essential than its solution, which may be a matter of mathematical or experimental skill. To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advances in science. - Albert Einstein
You cannot cheat nature, however much you may cheat your fellow man. - Galileo
Your understanding of the facts that establish the natural eye's behavior will eventually determine your success in avoiding myopia.
There are two categories of facts that must concern you. If I tell you that there are more than one million stars in the universe, you might believe me. If I tell you that the paint on a bench is wet, you will reach out and touch the bench. The facts that I present must be as clear and convincing to you as wet paint on a bench.
The facts presented in this book can always be confirmed by yourself in the same manner that you would confirm that a park bench has wet paint. If you ran your own experiments you would find that the normal eye can be driven towards nearsightedness by either a negative lens or a confined environment. Understanding this fact is crucial to understanding the normal eye's behavior.
The next step is to recognize that your eyes behave the way that all normal eyes behave. By substantially changing your near environment into a "far" environment you can successfully recover from a slight amount of myopia. This requires that you have a logical, self-disciplined mind that will go from fact recognition, to a process of implementing a solution that meets your personal needs.
The use of a lens to deal with any and all problems of the eye began in the 14th century. The practice of using a negative lens for nearsightedness has continued, almost unchanged, for the last 300 years. The compelling reason for this practice is the public's demand for an instant solution, and a corresponding refusal to consider the use of an alternative approach.
We should all thoughtfully evaluate the unfortunate effect of using an immediate and easy fix for the problem of nearsightedness. This situation of a self-perpetuating mistake (produced by public need and attitude) is sometimes recognized by the students of medicine. Dr. Perri Klass said it this way in VITAL SIGNS:
"... Sometimes the awesome weight of medical knowledge is totally off the beam. You have to practice medicine with that in mind, with the knowledge that a hundred years or so along the road, they'll be telling stories about the medical theories of today to get a laugh of the medical students of 2085..."
And about medicines' confidence in its routines:
"... Or something so basic, so taken for granted, that no one has gotten around to questioning it. Whatever it is, probably the medical profession is collectively doing something really dumb and really damaging, and doing it with complete good will and typical medical self-confidence."
This applies to vision. The demand for negative lens use comes partly from the public's demand for an instant solution, (and corresponding reluctance to properly use a plus lens) and not from a scientific assessment of the behavior characteristic of the normal eye.
Much of this book concerns testing and verification of the natural eye's behavior. This work, although absolutely essential, cannot give you immediate guidance in your effort to get yourself out of a slight amount of nearsightedness. You should, however, read on in order to understand the following optical principles.
The positive lens, when properly used, will change a near environment into a "far" environment. This is the desired objective.
THE PLUS LENS MAKES DIVERGING RAYS OF LIGHT PARALLEL THUS KEEPING THE NATURAL EYE IN AN "OPEN" ENVIRONMENT
Subjectively, the lens (which is a low-power magnifying glass) makes the object look slightly larger. People have reported that the lens reduces eye-strain caused by close work. The lens has been used for over a century for this purpose, and it is recommended and used by the eye-care profession. The plus lens is regarded as absolutely safe for all reading.
Such a lens must have a strength of greater than +1.5 diopters if the glasses are to achieve the desired result in a reasonable period of time.
Because a positive lens is not a prescription lens, the glasses are sold in almost all pharmacies. They sell for about $10 to $12, and are rated in terms of diopters and/or focal length. A 2.0 diopter lens would be used at 20 inches, and has a focal length of 20 inches. If you habitually read at 25 inches then you would use a 1.75 diopter lens. The power of the lens is normally stamped on the bow of the glasses.
If you wish to determine the focal length (power) of the glasses by direct measurement, hold them up in sunlight above a flat surface. Move the lenses up and down. Find the distance where the sun forms the sharpest and smallest image. Then measure the distance from lens to surface. The focal length is the reciprocal of lens power:
|Distance In Inches||Focal Power|
|40 Inches||1 Diopter (Weakest)|
|20 Inches||2 Diopters|
|13 Inches||3 Diopters|
|10 Inches||4 Diopters (Strongest)|
Once you select the lens that you feel is best for you, (between 1.5 to 2.5 diopters) select some reading material. For a starting point, hold the reading material about twelve inches from your eyes. Gradually move the print away from your eyes and note the point where the print just blurs. This point should be your habitual reading distance. If you habitually read closer, you will need a stronger lens. If you read at a greater distance you need a weaker lens. Some experimentation is in order here, and you may try several pairs of glasses before you find the right pair for yourself. In general, stronger is better, but you will want to be comfortable with the lens you choose.
If you have never used lenses before, you will notice a slight disorientation when you read close (with the lenses on) and then look in the distance over the tops of the lenses. This is a good indication that the lenses are having their desired effect. The reason for this is that the lenses have placed the near work at a distance while the convergence system believes the work is close by. This situation is normal and is part of the price one must pay to avoid nearsightedness.
This chart is called the Snellen eye chart. In daylight, the normal human eye can resolve objects that are separated by about one inch at 100 yards. This is 1 minute of angle resolution. The typical eye chart displays letters that cover 5 minutes of angle. To read the letters on the chart requires the ability to separate the white space from the black space. This is the most common method of quickly determining the resolving power of the eye. Over the past 100 years, the standard distance for this measurement was set at 20 feet with normal room illumination. The letter size for 20 feet is 3/8 inch. The letter size for 20/40 vision is therefore 6/8 inch, and so forth.
Reading the eye chart is straight-forward. Place the chart at 20 feet and start reading from the bottom up. You will find variability in your readings. Some days you will be able to read the 20/20 line without difficulty. Other readings will drop to 20/40 or 20/60. As the plus lens begins to have the desired effect, you will find that you can more consistently read the 20/20 line.
We can use the Federal Aviation Administration's considerable experience in testing eyesight. The requirement for the First Class Medical Certificate (Airline pilot requirement) for flying, is the ability to read four out of five characters on the 20/20 line. You should check and double check your visual state by yourself so that you understand and trust the measurement. Use the FAA method of measurement as the standard. This measurement is made in a well-lighted room, with the eye chart at a distance of twenty feet. I recommend that you set up the eye chart (in the back of the book) and check your eyes as soon as possible.
In checking your focal status, you will determine either that you can or cannot read the 20/20 line. If you read the 20/40 line you will still pass the state test for a driver's license. (The 20/40 line translates into a focal state of about -1/2 diopter.) If as a potential military pilot you cannot read the 20/20 line your professional flying career will go on hold.
The Naval and Air Force Academy students (who are not offered the use of the plus lens) never recover from a slight amount of nearsightedness. It is also true that the Naval and Air Force Academy will not accept you for a flying career if you have less than naked eye 20/20. However, the Air Academy has recently relaxed its requirement, and will allow you to continue with less than 20/20.
The airlines have changed their policies -- somewhat. Delta categorically requires naked eye 20/20, but the other airlines have changed their requirements from a minimum of no worse than 20/30 (focal state -0.25 Diopters), to a minimum of 20/100. If you use a "quick fix", or negative lens, your vision will worsen, and there is a high probability that you will go below the Airline minimums, even with a waiver. It is a situation that you should wish to avoid.
The experimental data, and the testimony of scientists and ophthalmologists, indicates that you can recover from 20/60. It is obviously better to get out of nearsightedness. Given the choice between a nearsighted pilot and a non- nearsighted pilot, the airline will choose the pilot who can read the 20/20 line.
The approach recommended in this book requires that you wear the plus lens for almost all close work, and take over complete control of the situation. This requirement may perhaps seem a burden, but you must decide -- the inconvenience of plus lens use, or the loss of your career as a professional pilot with the loss of your distance visual acuity.
If your vision is 20/60, you should persistently wear your lenses and check your eyes once a week. You can personally determine when you can again read the 20/20 line. It may take from three to six months to again read the 20/20 line. Once you can read the 20/20 line you should continue using the plus lens for another two or three months. You should continue checking your eyes at monthly intervals -- just to make sure that you will be able to pass the FAA exam when you are required to do so.
If your myopia returns (after not using the plus lens for a while) you will have to start the process again. It is best if you control this entire process yourself.
While I strongly recommend that you use the simplest and least expensive approach (less that $100) to avoiding (and recovering from) nearsightedness, for sake of completeness I will discuss two other existing practices that will produce recovery.
This approach involves the physical cutting of the cornea (the transparent surface of the eye). The approach produces uncertain results, and costs approximately $ 3,000 per eye. The Air Force will reject you if you have this done, even if you obtain 20/20 vision.
In orthokeratology, a hard contact lens of larger radius than the cornea (see page 20) is used. This lens is force-fit onto the eye, thus changing the shape of the cornea. This approach costs from $1,000 to $2,000, and will produce vision restoration if your vision is on the order of 20/80.
Even if you read the 20/20 line when you enter a four-year college there is a good probability that you will fail the eye chart before graduation. You should monitor you eyes by placing the eye chart in your room and occasionally verifying that you can easily read the 20/20 line. When a day arrives that you cannot clearly see the 20/20 line you should initiate the plus lens procedure. It is better to know about this method beforehand so you will not panic when you get into the situation.
For the past 50 years, the U. S. military academies have been monitoring the focal behavior of the normal eye. They have determined that the average eye goes downhill at the rate of about -1/4 diopter per year. If one has a focal state of zero diopters on entry, one has about a 10 percent chance of graduating with 20/20 vision. If the focal state is +1.0 diopters one has about a 90 percent probably of graduating with 20/20 vision, although the focal status will have changed from +1.0 diopters to 0.0 diopters over the four years.
You could check your own focal state if you had the proper set of positive lenses to do so. Failing this, you should find a cooperating optometrist or ophthalmologist who will check you focal status. Make a note of this measurement. If the value is + 1.0 diopter for each eye you will almost certainly graduate with 20/20 vision. If the value is 0.0 diopters, you can be almost certain that without intervention you will sink below the 20/20 line during your four years of intensive work.
A number of eye-measurement approaches are used by the eye profession. Some eye Doctors will use a small "box" with an eye chart which you look into. Others will have you read an eye chart in a darkened room. These different methods of measurement will produce different and inconsistent readings. If you are told you have 20/40 vision in a darkened room, you may find that you have 20/20 in a well lighted room.
If you find that you can read 20/20 line, and you have recently received negative lenses for nearsightedness, you should find an FAA medical examiner, make an appointment, read the eye chart for him, and get the "must wear negative lenses" requirement removed from your FAA license. You should, in addition, still use the approach described in this book to insure that you never again get back into nearsightedness!
You will undoubtedly get advice from many sources. Much of this advice will be confusing and contradictory. Each group has its own vested interest. The health profession must cater to everyone, and its procedure must work instantly on everyone. Health professionals cannot easily sort out who will take the initiative to make the preventative effort work successfully. Some have (privately) recommended the approach suggested in this book.
For at least twenty years scientists have recognized the reason and the need for plus-lens use to prevent the occurrence of nearsightedness.
It is impossible to impose prevention or conduct a preventative study until each individual is aware of the history of the problem as well as the nature of the probable solution.
For the past twenty years the medical and health community has consistently advocated prevention with the plus lens.
Faced with a public misconception about the use of lenses for the eye, the doctor (who must deal with the public) is forced to follow the tradition of the last 300 years -- regardless of the long-term consequences. The health profession has recognized that the situation requires a strong personal preventative effort but is unable to persuade most individuals to consider and use the alternative approach.
The consequence of a careful review of the experimental data that clearly establishes the behavioral characteristic of the normal eye causes us to reject the idea that a positive or negative focal state of the eye represents any defect of the eye. The normal eye always controls its long-term focus. The use of a negative lens when you are on the threshold of the situation virtually guarantees that your nearsightedness will worsen and become non-recoverable.
The only way you personally can be certain that you understand the normal eye's behavior is to perform the critical experiments yourself. If we desire almost absolute proof that the normal eye is a dynamic system, then we must develop a mathematical concept of the eye's behavior and rigorously test that concept.
Care for the defective eye is a responsibility that is thrust upon the health profession. The responsibility for dealing with and judging the normal eye's performance is a scientific responsibility. These two responsibilities are often confused.
In the past would-be pilots have become nearsighted with no intimation of a solution. Nor has any warning been explicitly provided to these young men about the inherent danger of negative lens use. The tragedy is not that nearsightedness develops with predictable and monotonous regularity but rather, that the would-be pilot (who would desperately like to get out of the situation) is not adequately warned and offered a practical alternative.